<?php
/**
 * Created by PhpStorm.
 * User: liuda
 * Date: 2019/2/22
 * Time: 15:12
 */

namespace app\common\utils;


trait Singleton
{
    private static $_instance = null;

    public static function getInstance(){
        if(null === self::$_instance){
            self::$_instance = new self();
        }
        return self::$_instance;
    }
}